Photoelectric inspection of containers for dirty finishes



Feb. 15, 1966 H. R. ROTTMANN PHOTOELECTRIC INSPECTION OF CONTAINERS FOR DIRTY FINISHES VENTOR. JM M/XJM? Filed Dec. 1, 1961 Q. M ATTOR NEYS United States Patent 3,235,740 PHOTOELECTRIC INSPECTION OF CONTAINERS FOR DIRTY FINISHES Hans R. Rottmann, Toledo, Ohio, assignor to Owens- Illinois Glass Company, a corporation of Ohio Filed Dec. 1, 1961, Ser. No. 156,396 3 Claims. (Cl. 250-224) This invention relates to a method and apparatus for inspecting the finish or closure attaching portion of a transparent glass container. More particularly this invention relates to a method and apparatus utilizing optical principles for inspecting container finishes for dirt or other contamination which may be present thereon as a result of the forming process of making the containers.

It is an object of this invention to provide a method of inspecting the finish of a glass container to determine the presence or absence of mold dope or other contaminating substances thereon.

It is an additional object of this invention to provide apparatus for inspecting finishes of glass containers for dirt or other foreign substances.

It is a further object of this invention to provide a method and apparatus for inspecting glass articles for the presence of dirt thereon which utilizes a diffuse source of illumination for an optical inspection.

Other and further objects and advantages will be apparent from a consideration of the following disclosure taken in connection with the drawings in which:

FIG. 1 is a side elevational view partly in section of the inspection device of the invention, and

FIG. 2 is a left side view of the mask of FIG. 1.

Referring to FIG. 1 a container C, to be inspected, is supported by a table 10. The table is supported by a rod 11 and is adapted to be rotated by the rod. In this manner the container C is rotated. Vertically spaced from and above the table 10 is a fixed support 12 to which are adjustably attached a pair of spaced rods 13 and 14. The rods 13 and 14 are maintained in adjusted position by a pair of bolts 15 which are threaded through the support 12 and engage the rods 13 and 14 which extend through vertical openings provided in the support 12.

The lower ends of the rods 13 and 14 are connected together by a horizontal bar 16 which serves as the support for a mask 17. The mask 17 is carried at the lower end of a rod 18 which extends through an opening provided in the bar 16. The rod 18 has, at its upper end, a crosshead member 19 which bears against the end of a thumb screw 20. The thumb screw 20 is threaded in an opening provided in the bar 16 and by rotation thereof may be vertically adjusted. The rod 18 also has a shoulder portion 21 formed thereon adjacent its connection to the mask 17 and a biasing spring 22 surrounds the rod 18 and bears at its upper end against a bar 16 and at its lower end against the enlarged portion 21 of the rod 18. In this manner the mask 17 is biased in a downward direction to a certain extent and its vertical position with respect to a container within which it is positioned, is adjustable by adjustment of the thumb screw 20. Vertically above the crosshead 19 is positioned an electro-magnet having a soft iron core 23 and having wound therearound a suitable number of turns of wire 24. The wire 24 is connected by leads 25 and 26 to a battery 27 or other suitable source of direct current. In the lead 26 there is provided a switch 28 which may be opened or closed depending upon whether it is desirable to energize the electro-magnet. Closing of the switch 28 will complete the circuit through the wire 24 and magnetize the soft iron core 23. The crosshead 19, formed of a magnetizable material, Will be attracted by "Ice the electro-magnet to cause the crosshead and mask 17 to be moved vertically a distance sufiicient to withdraw the mask from the finish portion of the container C.

In this manner the container may be easily removed from the table 10 and another container to be inspected may be inserted in place thereof.

As best shown in FIG. 2, the mask 17 is semi-circular in configuration and has an aperture 29 formed therein at the center thereof. The aperture 29 should have a vertical length which is at least equal to the vertical height of the finish portion of the container to be inspected. The mask 17 is formed with a pair of channels 30 and 31 adjacent its top and bottom and which are in facing relationship. These channels serve as the supporting means for a translucent light diffusing material 32. This material may be, for example, translucent plastic or any material which has the property of dilfusing light passed therethrough. The translucent material 32 is exposed, through the aperture 29 formed in the mask 17, to a source of light provided by a conventional light bulb 33. The light bulb has a filament 34 which glows upon excitation by a suitable current fed thereto through the leads 35. The bulb is supported in a housing 36 which also supports a condensing lens 37 which will focus an image of the filament 34 onto the aperture 29 formed in the mask 17. It should be understood that the image of the filament will be slightly larger than the aperture 29 to provide uniform illumination of that portion of the translucent material overlying the aperture.

In this manner the translucent material 32 will illuminate a portion of the finish of the container with diffused light. The illuminated portion of the finish of the container is viewed by a photo-sensitive means, generally designated 38. The photo-sensitive means takes the form of a photoelectric cell 39 mounted in the end wall of the cylindrical housing 40. Cell 39 has an opaque coating with only a relatively small, uncoated area facing in the direction of the longitudinal axis of the inspection device. Whether the finish is focused on the clear area or on the cathode of the cell is not critical because the distance from the clear portion of the cell to the cathode is many times smaller than the distance from the lens to the photocell. The forward end of the housing 40 telescopically receives a cylindrical member 41 which serves as the support for a condensing lens 42. The member 41 is axially shiftable with respect to the housing 40 and may be retained in adjustable position by a clamping screw 43. The axial adjustment of the member 41 permits shifting of the lens 42 so as to focus an image of the illuminated finish portion of the container onto the photoelectric cell 39. The photoelectric cell 39 is connected by leads 44 and 45 to a voltmeter 46.

Thus it can be seen that illumination of the translucent material will provide a source of diffuse light in close proximity to the neck or finish portion of the container and inasmuch as the aperture 29 is relatively narrow, in the order of to of an inch, a narrow section of the total circumference of the container finish portion will be illuminated and upon rotation of the container, successive portions of the container finish will be illuminated. Complete rotation of the container through 360 will, of course, illuminate the entire circumference of the finish portion of the container. The photosensitive means 39 will have an output voltage depending upon the intensity of the light transmitted through the finish portion of the container. If the finish portion is clean and free of any specks caused by mold dope, the voltmeter 46 will provide a steady reading, however, if a speck of mold dope is present on the finish portion of the container, as this speck passes into the area of illumination it will mask a portion of the light being transmitted through the container finish and the voltmeter 46 will immediately indicate a reduction in intensity of the light transmitted. The specks which may appear are primarily caused by combustion of mold dope which is sprayed within the neck molds of a container forming machine andmay becomestuck to the outer finish portion of the container. These specks usually consist of pieces of graphite which are opaque thus masking the transmission of light out of the finish portion.

By providing an apertured mask covered by a translucent material, a relatively small area of the finished portion of the container is illuminated thus the interpositioning of a speck between the source of diffused light and the photocell will decrease the intensity of light transmitted to thelphotocell, an amount sufficient to provide a distinct response in'the voltmeter 46.

From the standpoint of operability of the inspection device of the invention, it is necessary to use diffused light as the finish portion illuminating means. Diff-used light when passing through the irregular outer surface of the finish portion of the container, will not be reflected from this irregular outer surface to the extent that incident light would be reflected, thus providing a substantially constant voltage indication for clean container finishes.-

While applicant has described a convenient manner of providing a source of diffused light for illuminating the small radial portion of the container finish, it should be pointed out that the rod 18 could serve to support a bulb having a light diff-using surface in close proximity to the aperture 29 in which case the translucent material covering the aperture 29 would be unnecessary. Furthermore, other and different means could be provided for raising and lowering the mask 17, for example, the rod 18 could be vertically shifted by means of a hydraulic motor fixed to the support 12. A further alternative, a horizontally disposed electric motor having its output shaft connected toa crank arm with the end of the crank arm connected to the rod 18 would also provide means for raising and lowering the mask 17.

- Various modifications may be resorted to within the spirit and scope of the appended claims.

I claim:

1. Apparatus for inspecting the finishportion of a glass container for mold dope or specks of dirt comprising means for rotating a container about its vertical axis in an upright position, a curved mask having a narrow vertical aperture therein of a length corresponding to the height of the finish portion to be inspected, means for positioning said mask within the finish portion of the container in close proximity to the inner surface thereof,

a light diffusing material carried by said mask in overlying relationship to said aperture, a light source positioned outside of said container, means for focusing said light source onto said aperture for illuminating a narrow, vertical portion of said light diffusing material on the side opposite that facing the container surface, a photosensitive detector positioned outside the finish portion of said container in horizontal alignment with said aperture in said mask, and indicating means connected to said detector for indicating the intensity of light passing through said container finish whereby mold dope or dirt specks will be detected by a variation in the transmission properties of said finish portion. 2. Apparatus for inspecting the finish portion of glass container for mold dope'or specks of dirt comprising means for rotating a container about its vertical axis in an upright position, a curved mask having a narrow vertical aperture therein, means for positioning said mask within the finish portion of the container in close proximity to the inner surface thereof, said means for positioning said mask comprising an electromagnet mounted above the mask, a cross-head connected to said mask, a spring normally urging said mask in a downward direction, means for selectively energizing said electromagnet to lift said mask out of said container after completion of the inspection thereof, a light diffusing material carried by said mask in overlying relationship to said aperture, a light source positioned outside of said container, means for focusing said light source onto said aperture for illuminating a narrow, vertical portion of said light diffusing material, and a photosensitive detector positioned outside the finish portion of said container in horizontal alignment with said aperture in said mask, whereby said detector will provide an indication of the intensity of References Cited by the Examiner UNITED STATES PATENTS 2,265,037 12/1941 Gulliksen 88l4 2,446,377 8/1947 Marshall 250223 X 2,735,017 2/1956 Beard et al 88l4 X 3,027,798 4/1962 Mathias 88- 14 3,098,565 7/1963 Fouse et al. 88l4 RALPH G. NILSON, Primary Examiner. 

2. APPARATUS FOR INSPECTING THE FINISH PORTION OF A GLASS CONTAINER FOR MOLD DOPE OR SPECKS OF DIRT COMPRISING MEANS FOR ROTATING A CONTAINER ABOUT ITS VERTICAL AXIS IN AN UPRIGHT POSITION, A CURVED MASK HAVING A NARROW VERTICAL APERTURE THEREIN, MEANS FOR POSITIONING SAID MASK WITHIN THE FINISH PORTION OF THE CONTAINER IN CLOSE PROXIMITY TO THE INNER SURFACE THEREOF, SAID MEANS FOR POSITIONING SAID MASK COMPRISING AN ELECTROMAGNET MOUNTED ABOVE THE MASK, A CROSS-HEAD CONNECTED TO SAID MASK, A SPRING NORMALLY URGING SAID MASK IN A DOWNWARD DIRECTION, MEANS FOR SELECTIVELY ENERGIZING SAID ELECTROMAGNET TO LIFT SAID MASK OUT OF SAID CONTAINER AFTER COMPLETION OF THE INSPECTION THEREOF, A LIGHT DIFFUSING MATERIAL CARRIED BY SAID MASK IN OVERLYING RELATIONSHIP TO SAID APERTURE, A LIGHT SOURCE POSITIONED OUTSIDE OF SAID CONTAINER, MEANS FOR FOCUSING SAID LIGHT SOURCE ONTO SAID APERTURE 